New Apple Watch support documentation released by Apple might not pleasing for body art fanatics. As written in the newly released documentation, Apple Watch will face disruptions in its functionality if you happen to have tattoos on your wrist.

Apple says that tattoos won’t be much friendly with Apple Watch and will not offer an accurate heart rate monitoring. Existing Apple Watch owners have been expressing mixed emotions on discussion forums and social networking websites about the same. Few said heart-rate functionality works fine with their tattoos, others complained of getting no reading at all. Witnessing all those complaints, Apple updated its support documentation.

Permanent or temporary changes to your skin, such as some tattoos, can also impact heart rate sensor performance. The ink, pattern, and saturation of some tattoos can block light from the sensor, making it difficult to get reliable readings.

Apple has also explained the tech it is using and why any sort of skin pigmentation is causing the heart rate sensor to malfunction. The Cupertino giant says,

Apple Watch uses green LED lights paired with light‑sensitive photodiodes to detect the amount of blood flowing through your wrist at any given moment. When your heart beats, the blood flow in your wrist — and the green light absorption — is greater. Between beats, it’s less. By flashing its LED lights hundreds of times per second, Apple Watch can calculate the number of times the heart beats each minute — your heart rate.

That makes it clear, if you have a dark color inked to you wrist, you might have to reconsider before buying an Apple Watch. The watch tracks heart rates through a common medical technique that measures how much light is absorbed by blood. And, it is pretty much obvious that it would also disrupt other fitness bands that rely on same technique (as was the case with FitBit a while back).

Certain experts are also saying, that it isn;t just Tattoos which will affect the heart rate sensor. Pigmentation in skin through any mechanism, will also cause the heart rate sensor in Apple Watch to dysfunction.

Unfortunately, Apple also uses those sensors to detect when the Watch has been removed from a person’s wrist. If the Watch doesn’t think it’s being worn, it won’t receive notifications; it can also cause the Watch to lock if a passcode is enabled.

Apple Watch uses green LED lights paired with light‑sensitive photodiodes to detect the amount of blood flowing through your wrist at any given moment. When your heart beats, the blood flow in your wrist — and the green light absorption — is greater. Between beats, it’s less. By flashing its LED lights hundreds of times per second, Apple Watch can calculate the number of times the heart beats each minute — your heart rate.